Iron with self-cleaning sole plate

ABSTRACT

The invention relates to an iron comprising a sole plate which forms the ironing surface. An oxidation catalyst, which is active on organic dirt, covers the ironing surface. Said catalyst is active when the soleplate reaches a temperature which is at least equal to or higher than 90° C.

The present invention relates to pressing irons.

Pressing irons have qualities of ease of use and efficiency dependinginter alia on the state and the nature of the ironing surface of theirsoleplate. Soleplates have been able to be improved by the care broughtto the sliding qualities of the ironing surface, combined with qualitiespermitting easier spreading out of the laundry. One manner of obtainingthese qualities is to resort to enameled soleplates with an enamelhaving a smooth appearance, with possibly raised lines permittingspreading of the fabric during displacement of the iron. Other metalsoleplates mechanically treated and/or covered or not with a deposit tofacilitate sliding can equally be suitable for a satisfactory usage.

However, during use, the soleplate can be tarnished by carbonizing in amore or less diffuse manner on the ironing surface, and in a more orless incomplete manner, various organic particles trapped by rubbing onthe fabrics being ironed.

But when the soleplate is tarnished even in a manner that is hardlyvisible, it partially loses its sliding qualities. Imperceptibly, withthe soiling, the ironing becomes more difficult. Moreover, the userbecomes apprehensive of using a tarnished iron, fearing that it canalter the laundry.

Pressing iron soleplate coatings are known that have a hard and durablelayer covered, as indicated by the patent U.S. Pat. No. 4,862,609, by alayer improving its surface properties. But this patent does notindicate a solution for combating soiling.

The object of the invention described herebelow is a self-cleaningpressing iron, the soleplate of which is maintained clean of anycontamination by organic particles and is not clogged by normal usage,in a manner to retain its initial qualities.

The goal of the invention is achieved by a pressing iron having asoleplate, the outer surface of which comprises the ironing surface,characterized in that an oxidation catalyst having an oxidationcatalytic agent is present or distributed in and/or on a surface layerof said soleplate, said oxidation catalyst being active with respect toorganic dirt at a temperature at least equal to 90° C.

Due to the invention, during ironing, organic particles captured by thesoleplate are oxidized. They are to some extent burned when the pressingiron is hot, the possible solid residue loses all adherence and isdetached from the soleplate. The soleplate is maintained clean.

In fields very different from ironing, an oxidation catalyst has alreadybeen associated with an external surface of a support.

Enameled self-cleaning surfaces are known, for example in ovens andcooking utensils such as described for example in the patent U.S. Pat.No. 4,029,603 or the patent FR 2400876.

The patent U.S. Pat. No. 4,994,430 describes an enameled coating havinga dense layer and at the surface a porous layer supporting a catalyst.But such a thick, porous layer is incompatible with ironing.

There is also known from the patent U.S. Pat. No. 5,388,177 adeodorizing heating element, the enameled surface of which is coatedwith a catalyst, but the catalyst is provided only for deodorizing.

In any case, the solutions described in these documents cannot beapplied to a pressing iron, since one could fear in particular that, onthe one hand the requirements of low roughness for the ironing surfaceare opposed to the retention of the oxidation catalyst, and on the otherhand the rubbing resulting from the ironing rapidly removes theoxidation catalyst from the external surface of the ironing soleplate.

The oxidation catalyst is distributed on and/or in the surface layer ofthe iron, where it is in contact with the dirt, or stains.

In practice, the oxidation catalyst is present and/or distributed on thesurface over all or part of the outer surface of the soleplate.

Thus, the oxidation catalyst can be present or distributed betweenpredetermined zones of the outer surface of the soleplate, for examplein the recessed zones of the outer surface, susceptible to capturing oraccumulating dirt and in general hotter than the ironing surface, whichis favorable for oxidation or catalytic.

When the outer surface of the soleplate has one or several parts thatare recessed with respect to the remaining flat part, forming the usefulsurface or the ironing surface proper, the oxidation catalyst is presentor distributed in the recessed part or parts, to the exclusion of theironing surface.

But, of course, the oxidation catalyst can be present, over all or partof the ironing surface proper.

The catalytic oxidation agent considered according to the presentinvention is thus any element, compound or composition capable ofoxidizing, at a temperature at least equal to 90° C., any organicsubstance such as contained in the dirt, or stains, presentlyencountered in the treatment (including washing and possibly softening)of textile articles or pieces (for example linen).

Such a catalytic oxidation agent can be specific or non-specific for oneorganic substance or another.

In practice, the oxidation catalyst can have or not, in addition to thecatalytic oxidation agent, an inert support, for example in divided orparticle form, for example alumina, at the surface (includinginternally) of which the catalytic oxidation agent is distributed ordispersed. The inert support can itself constitute, in the non-dividedstate, the surface layer that will be discussed herebelow.

As examples of catalytically active elements, one can cite palladium,platinum, vanadium, copper or any composition of such catalyticallyactive elements (in terms of oxidation). In the active catalyticcompositions considered according to the present invention, there can bepresent oxides of copper, manganese or cobalt, increasing the catalyticeffectiveness or the stability of the catalytic agent.

In practice, such oxidation catalysts are well known per se, as well asthe processes for obtaining them, without there being a need to describethem by the details of their methods of preparation respectively. Thus,by way of example, in the matter of platinum as a catalytic oxidationagent, its catalytically active form can be obtained by calcination ordecomposition of a chloro-platinic acid salt or any other precursor.

Of course, any oxidation catalyst retained according to the presentinvention should remain sufficiently stable at the working temperatureof the ironing surface, and this within the limits of the useful life ofthe pressing iron.

In practice, the oxidation catalyst according to the invention is founddistributed at least in and/or on the surface layer of the soleplate ofthe pressing iron. By “surface layer”, there is intended any limitinglayer, of which the thickness can, by way of example, be at least equalto 500 nanometers and particularly comprised between 20 nanometers and120 nanometers in contact at one side with another layer or thesubstrate of the soleplate and providing at the other side an interfacewith the outside, having the ironing surface proper. The oxidationcatalyst or the catalytic oxidation agent can be distributed over all orpart of the outer surface of the soleplate, in the thickness and/or onthe above-cited outer layer, in a continuous or discontinuous manner.

By “ironing surface”, there is intended all or the useful part of theouter surface of the soleplate, coming directly in contact with thelaundry during ironing.

When the oxidation catalyst remains on the surface layer of thesoleplate, it can form a layer or a film that is continuous ordiscontinuous.

The above-cited surface layer cannot be distinguished from the rest ofthe soleplate, of its substrate, or of a constituent layer of thislatter, in which case, in the present description and in the followingclaims, use of the term “surface layer” only has the object ofdistinguishing the limited thickness, possibly zero, of the soleplate,in which the oxidation catalyst or the catalytic oxidation agent can bedistributed and incorporated.

The thickness of the surface layer in which the catalyst or catalyticoxidation layer can be comprised depends particularly on the depth ofmigration of organic dirt into the interior of the soleplate of thepressing iron, starting from the outer surface.

By “organic dirt”, there is intended any substance that is combustibleor oxidizable on contact with ambient air, completely or partially. Byway of example, one can cite any residue of synthetic fibers, such asused in textile articles, for example in organic polymers such aspolyamide or polyester or any residue of washing products or possibly ofsoftening products.

By of example, the catalytic oxidation agent comprises a metal of groupIV of the periodic table or a noble metal, for example palladium and/orvanadium.

The oxidation catalyst being active at a soleplate temperature greaterthan or equal to 90° C., it cleans said soleplate when it is hot.

In a first mode of operation, the catalyst acts at the ironingtemperature of the iron, and the soleplate is maintained cleanpermanently to the extent that the iron is used for ironing.

In a second mode of operation, during a phase called self-cleaning,before or after use of the pressing iron, the iron is regulated to anelevated temperature equal to or greater than the highest ironingtemperatures. It is then left alone during a predetermined time, duringwhich the oxidation catalyst produces its effect. The user can thusmaintain the iron regularly, without awaiting a harmful soiling.

In a first version, the iron has a metal soleplate clad with an enamelhaving a low porosity and/or roughness at the micrometric and/ornanometric scale, and the oxidation catalyst belongs to the surfacelayer of the enamel cladding. The enamel is, for example, a vitrifiedenamel.

Such an enamel is chosen from among the enamels having a low porosity,for example vitrified, known for their ironing qualities, this incomparison with the enamels used in ovens or on grills, which beingporous require needlessly the deposit of a substantial quantity ofoxidation catalyst and do not have the qualities required for asoleplate of a pressing iron.

The enamel should in effect at least be hard, have good sliding propertyand resist the penetration of steam or warm moisture.

The attainment or the application of the oxidation catalyst or of thecatalytic oxidation agent on or in the above-cited surface layer can beperformed by any known means such as by the application of any precursorof the catalytic oxidation agent, then baking by using a pyrolyticprocess or by electrophoresis or by chemical deposition without currentcalled “electroless” or by vapor deposition.

By “precursor”, there is intended any chemical or physico-chemical formof the oxidation catalyst and/or of the catalytic oxidation agent whichis capable of ending with or liberating this latter by any appropriatetreatment, for example pyrolysis. By way of example, any chloro-platinicacid salt is a precursor for the platinum considered as an oxidationcatalyst.

As shown by the examples herebelow, the choice of the composition of theoxidation catalyst or of the catalytic oxidation agent, and/or thecondition of obtaining or application of this latter are determined tonot substantially alter the intrinsic qualities of the ironing surface,notably its glide.

In a second version, the pressing iron has a metal soleplate, forexample an aluminum alloy, and a surface layer is added to the outersurface of said soleplate, in the form of a thin layer of a support, forexample alumina, for said agent for catalytic oxidation of said organicdirt.

By way of variation, the soleplate is clad with a layer of a polymerresistant to all oxidation at high temperature, for examplepolytetrafluoroethylene, and the surface layer belongs to said polymerlayer.

In a third version, the surface layer consists of a thin layer of theoxidation catalyst, comprising an inert support, for example alumina,and a catalytic oxidation agent supported by said support.

In a general manner, the invention also concerns the use of an oxidationcatalyst as a self-cleaning agent for all or part of the outer surfaceof the soleplate of a pressing iron.

The invention will be better understood from a reading of the followingexamples and the attached drawings.

FIG. 1 is a cross-sectional view of a soleplate of a pressing ironaccording to the invention.

FIG. 2 is a bottom view of a pressing iron according to the invention,showing the lower face of the soleplate.

EXAMPLE 1

In a first example of realization, pressing iron 1 visible in FIG. 1 hasa soleplate 2 of aluminum fixed to a heating base 3 of molded aluminumand furnished with a heating element 4. Soleplate 2 is coated on itsexternal surface 5 more easily visible in FIG. 2 by an enamel known forits ironing qualities. The catalyst or catalytic oxidation agent isdeposited in a very thin layer on the outer surface. This outer surface5 has the ironing surface 51 proper, and recessed parts 52, 53 forexample around steam outlet orifices 6.

For this purpose, the outer surface is degreased and activated by alight acid attack, for example with a citric or nitric acid solution. Aprecursor of the catalytic oxidation agent is prepared, for example bydissolving palladium nitrate in water at a rate of 2 grams of palladiumnitrate per liter. Moreover, several companies, for example the companyPCAS of Longjumeau, France, furnish more developed precursors. Thesoleplate being heated to around 300° C., the precursor is applied insolution on the soleplate by allowing it to pass below an ultrasonicatomizer, in one or several passes, to obtain a good homogeneity of theapplication. The assembly is baked at around 300° C. The thickness ofthe layer of oxidation catalyst (palladium) thus obtained can vary from20 to 120 nanometers. Preferably, the device is regulated to obtain athickness of the order of 30 nanometers. One notes that the deposit ofpalladium is adherent to the ironing surface, and does not disturb theglide characteristics of the underlying enamel in a noticeable manner.

The effectiveness of the oxidation catalyst can be measured in a closedenclosure. A sample of the soleplate is heated to 300° C., on which isdeposited a piece of fiber, of organic polymer, of 2 mg, meltedrepresentative of dirt. After having dosed the initial quantity ofcarbonic gas into the enclosure, one notes its increase, attesting tothe effectiveness of this solution.

In the example thus described, there was obtained a catalytic activityat 300 degrees having permitted production of 107×10⁻⁶ moles of carbonicgas per hour, for a catalytically surface, sample, of 10 squarecentimeters.

EXAMPLE 2

In a second example of realization, the enameled soleplate is heated to300 degrees. A solution comprising alumina in suspension is prepared bymixing 4 grams of tetraethylorthosilicate with 96 grams of nitric aciddiluted to 0.6%, to which is added 12.8 grams of “DISPERSAL S”. Thislatter alumina based product is furnished by the company CONDEA. Thesolution diluted 10 times is sprayed on the soleplate. The soleplate ismaintained at 300 degrees during one hour. The spraying is regulated toobtain a deposit in solid form of around 10 micrometers thickness, of asupport of catalytic oxidation agent that is alumina based. Then anaqueous solution of palladium nitrate is sprayed, which is subjected tobaking at 300 degrees for one hour.

With respect to the preceding example, the activity of a same activecatalytic surface, sample, is brought to 175×10⁻⁶ moles of carbonic gasproduced per hour.

EXAMPLE 3

In a third example of realization, the iron has an aluminum soleplate.The ironing surface is cleaned by a sodic attack followed by aneutralization and a rinsing. The soleplate is oxidized in an oven at560 degrees for 30 minutes, then there is applied by spraying a solutionof palladium nitrate at 2 grams per liter. After baking at 300 degreesfor one hour, one obtains a catalytically active or oxidation catalystsurface layer of around 30 nanometers thickness.

One obtains glide properties substantially similar to those of aluminum.The value of this realization resides in the economy of fabrication. Theactivity obtained is of the order of 112×10⁻⁶ moles of carbonic gasproduced per hour, for a catalytically active surface, sample, of 10square centimeters.

In a variant of this example of realization, the catalytic oxidationagent is incorporated in a surface layer of the Ormosil type, serving asa support, this term being an abbreviation for the English expression“Organically Modified Silicates”, as explained in the article“Structures and properties of Ormosils” of the Journal Sol-Gel Scienceand Technology, 2, 81–86, (1994), written by John D. Mackenzie.Preferably, the surface layer is obtained starting from a liquidsolution intended to produce a gel.

The catalytic oxidation agent is then deposited on and/or in thissurface layer, by a process similar to the preceding utilizing anultrasonic atomizer. One to four passes permit obtaining a goodhomogeneity. The assembly is then dried, then baked at around 300° C.

EXAMPLE 4

In a fourth example of realization, the iron has a stainless steelsoleplate. The ironing surface is cleaned then passivated in a 20%nitric acid bath. On the ironing surface heated to 300 degrees, there isapplied an alumina-based solution such as described in the secondrealization and the soleplate is maintained at 300 degrees for one hourin order to obtain a surface layer serving as a support for thecatalytic oxidation agent. A catalytic oxidation agent layer is thendeposited in and on this surface layer, by spraying with an ultrasonicatomizer a solution of palladium nitrate. The assembly is then driedthen baked at around 300° C. There is measured an effectiveness at 300degrees of 151×10⁻⁶ moles of carbonic gas produced per hour, for acatalytically active surface, sample, of 10 square centimeters.

In a practical manner, one notes a substantial difference of soilingbetween two irons, only one of which is provided with a self cleaningsoleplate according to the invention.

It is also noted that when a soiling is thick, it is consumed in thezone of contact of the oxidation catalyst, then separates from thesoleplate. Self-cleaning is obtained without awaiting completetransformation of the dirt.

Although the activity of the oxidation catalyst is manifested at the lowtemperatures of ironing, however greater than 90° C., this activity ismuch greater at higher temperatures. The user uses the pressing iron inthe usual manner. After an ironing session, if there is need, she actson a cleaning control button. This control modifies the assignedtemperature of the iron, to bring it to a temperature recommended forfunctioning of the oxidation catalyst, and marks the start of apredetermined self-cleaning phase, during which this temperature ismaintained, and beyond which the heating of the iron haltsautomatically. During this phase, the oxidation catalyst exerts its fulleffect. Dirt that can be adhered to the soleplate is consumed withoutdanger, this including in the zones of recesses 52, 53, after which theiron recovers all of its initial properties.

1. Pressing iron having a soleplate, the outer surface of whichcomprises the ironing surface, characterized in that an oxidationcatalyst having an oxidation catalytic agent is present or distributedin and/or on a surface layer of said soleplate, said oxidation catalystbeing active with respect to organic dirt at a temperature at leastequal to 90° C.
 2. Pressing iron according to claim 1, characterized inthat the soleplate is of metal and clad with a layer of enamel having alow porosity, and the surface layer is part of said layer of enamel. 3.Pressing iron according to claim 2, characterized in that the enamel isvitrified.
 4. Pressing iron according to claim 1, characterized in thatthe soleplate is clad with a layer of a polymer resistant to alloxidation at high temperature, and the surface layer is part of saidlayer of polymer.
 5. Pressing iron according to claim 4, characterizedin that the polymer is polytetrafluoroethylene.
 6. Pressing ironaccording to claim 1, characterized in that the soleplate is of metal,and the surface layer is added to the outer surface of said soleplate,in the form of a thin layer of a support for said agent for catalyticoxidation of said organic dirt.
 7. Pressing iron according to claim 6,characterized in that the support is made of alumina.
 8. Pressing ironaccording to claim 1, characterized in that the catalytic oxidationagent comprises a metal of group IV of the periodic table or a noblemetal.
 9. Pressing iron according to claim 8, characterized in that themetal of the catalytic oxidation agent consists of at least one ofpalladium and vanadium.
 10. Pressing iron according to claim 1characterized in that the surface layer consists of a thin layer of theoxidation catalyst, comprising an inert support, and a catalyticoxidation agent supported by said support.
 11. Pressing iron accordingto claim 10, characterized in that the support is made of alumina. 12.Pressing iron according to claim 1, according to which the outer surfacehas at least one part that is recessed with respect to the remainingflat part, forming the useful or ironing surface, characterized in thatthe oxidation catalyst is present or distributed in said recessed part,to the exclusion of the ironing surface.
 13. Pressing iron according toclaim 1, characterized in that the oxidation catalyst is present anddistributed between predetermined zones of the outer surface of thesoleplate, susceptible to capturing or accumulating said dirt. 14.Pressing iron according to claim 13, characterized in that thepredetermined zones of the outer surface of the soleplate are recessedzones of the outer surface.
 15. A method for inparting a self-cleaningproperty to at least part of the outer surface of the soleplate of apressing iron, comprising providing the outer surface of the soleplatewith an oxidation catalyst as a self-cleaning agent.